How can I change the name of file in the child's directory

Question

There is a child directory who name is stored in a variable called temp. I'd like to rename all files in that directory to their lower case version.

So I wrote this code:

mv ls $temp 'ls $temp | tr [:upper:][:lower:] [:lower:][:upper:]'

but it doesn't work. How can I change it?

Answer 1

You need a loop.

You can use Bash brace expansion to convert to lower case, instead of tr which creates an extra process each time:

#!/bin/bash
cd "$temp"
for f in *; do
  mv "$f" "${f,,}"
done

If you want to reverse the case of each character of the file name (thanks @SLePort for the tip):

#!/bin/bash
cd "$temp"
for f in *; do
  mv "$f" "${f~~}"
done